Service manual

Table 1–1 shows the major differences between the two platforms. Although
this manual does not cover the differences in detail, it does cover
the <REFERENCE>(2x) systems, the <REFERENCE>(xma2), and the
DWMBB in the XMI-2 cabinet. Other documentation covers upgrades (see
preface).
Power is distributed differently in the XMI-1 and XMI-2 backplanes.
Therefore, power considerations are important when servicing these
systems. Care must be exercised when replacing broken modules because
of incompatibilities.
The H7242 power regulator provides +3.3 volts to the XMI-2 backplane to
operate the VAX 6000 Model 500. The +3.3 volts is inhibited by a cable if
either a <REFERENCE>(xyp) or a <REFERENCE>(XRP) is in the system.
All XMI adapters have been designed to work on both backplanes with the
exception of the DWMBA. A new XMI-to-VAXBI adapter, the DWMBB, is
used to communicate between the two buses.
There are several ways to tell which cabinet houses your <REFERENCE>(rigel)
or <REFERENCE>(hyperion). Four are described here.
• Look at the cabinet number on the label on the bottom of the vertical
frame member at the left rear of the cabinet. If this label is hidden
from view by an SA70, you will have to use another method. If the
label indicates a 70 class part number, you have the XMI-1 platform.
If the label indicates an H9657, you have the XMI-2 platform.
• Open the rear cabinet door and look at the middle power regulator. If
the regulator is an H7242, it is an XMI-2 platform. Otherwise, it is an
XMI-1 platform.
• Open the rear cabinet door and look to see if the H7242 inhibit cable is
installed. This cable has a large yellow tag on it and is easy to see at a
glance.
• Open the rear cabinet door and look at the H7206 power logic unit just
above the H405 AC controller. If there are two connectors on the H7206,
the platform is an XMI-2. Otherwise, it is an XMI-1 platform.
For information on the XMI-1 power and packaging, see the VAX 6000–400
Options and Maintenance manual or the VAX 6200/6300 VAXserver 6200/
6300 Options and Maintenance manual. For information on the XMI-2
power and packaging, see the VAX 6000 Platform Service Manual.
Introduction 1–3